This project will develop an innovative echolocation device for blind infants. The commercial product will serve a large population of blind infants who at present have few alternatives to enhance their sensory capabilities and facilitate motor development. The proposed device: (a) is the only sensory substitution device for the blind to make use of the human ability to perceive bone conducted ultrasound; (b) makes use of the natural capacity for echolocation, rather than relying on processed sound, potentially facilitating the learning process, and making a more natural sensory substitution; and (c) by presenting the sounds in the ultrasonic region through bone conduction, it does not interfere with hearing of speech or environmental sounds. Evidence that bone- conducted ultrasound can be perceived through the vestibular sense even by the profoundly deaf suggests that this device could be of use for deaf-blind infants as well. The project will specifically demonstrate feasibility by a performance evaluation of the sonar parameters relevant to use by a blind infant, e.g. field of view, size and distance of object detection, and of the output to existing data on bone conduction thresholds and frequency discrimination.